Whisk together the soy sauce, lemon juice, olive oil, and Worcestershire sauce in a bowl to create the liquid base. Add the minced garlic, Italian seasoning, black pepper, salt, and red pepper flakes, stirring until fully combined. Tear the fresh rosemary sprig into smaller pieces and add it to the mixture. This combination of umami-rich soy and Worcestershire with bright lemon juice creates a well-balanced marinade that will penetrate and flavor the steak deeply.

Place the steaks in a large resealable bag or shallow bowl and pour the prepared marinade over them, ensuring they are well coated on all sides. Seal the bag or cover the bowl, then refrigerate for at least 2 hours, though overnight (8-12 hours) will give you the best flavor development. I find that marinating overnight allows the garlic and Worcestershire to really penetrate the meat, creating a more complex flavor profile.

Remove the steaks from the refrigerator 15 minutes before cooking to bring them closer to room temperature. Heat a cast iron or heavy-bottomed skillet over high heat until it's smoking hot—this ensures a proper crust forms. Place the steaks in the hot pan and sear for 3 minutes per side without moving them, allowing the exterior to develop a golden-brown crust that locks in the juices. This high-heat searing is crucial for building flavor through the Maillard reaction.

Reduce the heat to medium and continue cooking the steaks, flipping them every 3-4 minutes for about 10 minutes total, depending on thickness and desired doneness. I prefer to use a meat thermometer here—aim for 130-135°F for medium-rare, which gives you the best balance of tenderness and flavor. This lower-heat phase allows the interior to cook through gently while the exterior stays beautifully browned.

In the final minute of cooking, add the unsalted butter and fresh thyme sprigs directly to the pan, tilting it so the melting butter basts the steaks. This not only adds richness but also allows the thyme to infuse its oils into the butter, creating a luxurious finishing sauce. Transfer the steaks to a plate and let them rest for 5 minutes before plating—this allows the juices to redistribute throughout the meat.

Place the rested steaks on serving plates and drizzle with any remaining butter and pan juices from the skillet. Garnish generously with fresh parsley to add a bright, fresh finish that cuts through the richness of the meat and butter.